advent-of-code

Entries to advent of code, multiple years
git clone git://git.finwo.net/misc/advent-of-code
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index.js (1796B)

      1 const fs           = require('fs');
      2 const through      = require('through2');
      3 const line_by_line = require('../common/line-for-line');
      4 const nerdamer     = require('nerdamer/all.min');
      5 
      6 const step1 = {};
      7 const step2 = { equation: '', subst: {'humn':'x'} };
      8 
      9 // fs.createReadStream('sample')
     10 fs.createReadStream('input')
     11   .pipe(line_by_line())
     12 
     13   // Minor parsing
     14   .pipe(through.obj(function(line, enc, cb) {
     15     line = line.toString();
     16 
     17     const [id, definition] = line.split(':').map(s => s.trim());
     18 
     19     // Number = assign directly
     20     if (!isNaN(definition)) {
     21       step1[id] = () => parseInt(definition);
     22       if (id !== 'humn') step2.subst[id] = definition;
     23       return cb();
     24     }
     25 
     26     // Split & track substitution
     27     step2.subst[id] = definition;
     28     let [left, operation, right] = definition.split(' ');
     29 
     30     if (id == 'root') {
     31       step2.equation = `${left} = ${right}`;
     32     }
     33 
     34     step1[id] = () => {
     35       if (!right) return step1[left]();
     36       const l = step1[left]();
     37       const r = step1[right]();
     38       switch(operation) {
     39         case '+': return l + r;
     40         case '-': return l - r;
     41         case '/': return l / r;
     42         case '*': return l * r;
     43       }
     44     };
     45 
     46     cb();
     47   }))
     48 
     49   .on('finish', () => {
     50     console.log('loaded');
     51 
     52     // First do step 1
     53     const step1_result = step1.root();
     54 
     55     // Expand step2 equation
     56     let replaced;
     57     do {
     58       replaced = false;
     59       for(const [token,op] of Object.entries(step2.subst)) {
     60         if (~step2.equation.indexOf(token)) {
     61           replaced = true;
     62           step2.equation = step2.equation.replace(`${token}`, `(${op})`);
     63         }
     64       }
     65     } while(replaced);
     66 
     67     const solved = nerdamer.solveEquations(step2.equation, 'x');
     68 
     69     console.log({ step1: step1_result, step2: solved.toString() });
     70   });